1. Field of the Invention
The present invention relates to a method and an apparatus for automatically selecting a noise reduction circuitry at the time of a playback operation of a recording and playback apparatus.
2. Description of Background Information
Recording and playback apparatuses using a magnetic recording medium, such as tape decks, are generally provided with a noise reduction system to reduce the medium's inherent noise, that is, the tape hiss noise. With such a noise reduction system, conventionally, the selection of a noise reduction circuitry in the playback mode (i.e. the selection of an appropriate noise reduction circuitry, from among several noise reduction circuitries, which performs an operation complementary to the operation of the noise reduction circuitry used at the time of recording) is performed manually in accordance with the record or memory of the noise reduction circuitry used at the time of the recording.
In the case of an arrangement disclosed in Japanese Utility Model Kokai No. 58-56315, on the other hand, an ID signal indicative of the kind of the noise reduction circuitry is recorded on a tape at the time of the recording operation, thereby an automatic selection of a noise reduction circuitry is enabled by reading the ID signal at the time of playing back the signal recorded on the tape.
However, in the first case where the selection of noise reduction circuitry is performed manually, it is generally necessary to write various data relating the noise reduction operation, e.g., the ON/OFF state of the noise reduction, the type of the noise reduction circuitry used in the recording mode, into the label of the tape so that the user is able to know the type of noise reduction operation when playing back the signal recorded on the tape. It is, however, troublesome to operate the apparatus appropriately in the playback mode, and moreover there is a possibility that an erroneous selection of a noise reduction circuitry is made by the user. In case of the latter example where a noise reduction circuitry is automatically selected by using the ID signal, however, the system will not be able to select a noise reduction circuitry if no ID signals are recorded on the tape. Furthermore, it is necessary to provide a special recording area to record the ID signal on the tape, and also to provide a special magnetic head to read the ID signal. This means that the scheme using an ID signal cannot be used commonly in usual tape recorders.